Huh? How does dropping the i make it multicultural?
In each language Narnia has the i in it, so you'd leave the i in, obviously… I don't understand your example of ‘Kanado’ (nor ‘Usono’). The country is known in many languages as ‘Canada’ or similar. You didn't suddenly drop a letter from there to make ‘Kanado’.

I am not seeing why it could potentially be. Why drop the i? There is absolutely no reason to drop the i. I'm not saying you're wrong or anything, I am just trying to comprehend why you considered ‘Narno’ after the obvious ‘Narnio’ :p.
The reason that it is Ĉinio is because of the naming conventions of countries. It is based on ethnics or just the country (like Kanado, it's an international name). In this case, it is based on ethnics: ‘ĉino’. From there is the suffix -uj, so China is ‘Ĉinujo’. Later this was mostly replaced with the suffix -i (although -uj is always still correct) and so it became ‘Ĉinio’.
Of course they could have gone with ‘Ĉino’ for China and then call a Chinese person ‘ĉinano’. I don't know why that isn't the case, but it easily could have been.

In response to your recent comment, I'm not saying it would be "Narno." I'm saying it could potentially be. What's more, if "Canada" is "Kanado" solely because that's how it sounds in many languages, why is "China" "Ĉinio" instead of "Ĉino?"

If there were a city or a river within Narnia that was also named Narnia then it could hypothetically take the form of "Narno". New York is both a state (Novjorkio) and a city (Novjorko or sometimes Novjorkurbo). Colorado is both a state (Koloradio) and a river (Kolorado). But, to my knowledge no such river or city existed within Narnia, so "Narnio" is the only valid translation of the name.

That is not a good comparison. Again, the -i is being added here, because of the country naming conventions…
Give me an example where in English or so a name ends in -io or -ia or similar and the Esperanto name ends in -o without an i in front of it.

Maybe it is a backwards example. I was simply trying to show that, although there are instances when you do change the name, this isn't one of them. But, as long as we're being pedantic, Narnia contains countries, so its naming convention should probably follow that of planets rather than countries. ;)

If we are being pedantic, Narnia is used in three distinct geographic ways: there is the world of Narnia, the country of Narnia (one of several countries mentioned in the books), and the Great River of Narnia.

Well, four, actually. C. S. Lewis took the name from the Latin version of Narni, a town in Italy.

Ooh, I see! My bad; I kind of missed your point :s.
Aha, right! That would make more sense!

Anyway, to kind of wrap this whole thing up: stay as close to the original name as possible, stick as much to the -i suffix for states and countries and avoid ambiguities :). (In this particular case, if Narnia were to contain a river or so also named Narnia, I would rather go for the river Narno in Narnio over the river Narnio in Narniio :p (or just both Narnio).)

My very favorite book from my childhood. I still have the copy I was given by my uncle when I was seven years old. I then read ALL the Chronicles of Narnia, but none compared to my first experience with Peter, Susan, Edmund and Lucy xxx